1. Field of the Invention
This invention is directed toward a vision enhancement system, and more particularly toward a vision enhancement system which allows a user to view objects with normal perspective and scale under conditions of total darkness, or other conditions limiting normal vision. or adverse weather conditions.
2. Background of the Art
Clear vision with correct depth and size or scale perspective under adverse conditions is critically important in many situations. The following two examples are presented for purposes of illustration, but by no means fully describe the broad background of the art.
Night time military operations require a complete and accurate knowledge of the surroundings. Prior art systems such as radar, infrared imaging, laser based systems and the like have provided means for locating and ranging surrounding objects such as buildings, military equipment and even personnel under conditions of darkness and smoke. They are based upon the specific characteristics of the identified objects. As an example, radar identification systems depend upon, among other parameters, the object's electromagnetic reflectivity characteristics. As an additional example, infrared systems are based upon, among other parameters, the object's temperature contrast with the surrounding environs. Such physical characteristics might not be sufficient to fully identify the object. In addition, these prior art systems are typically large, are often mounted in a command post or vehicle, and are not designed to be comfortably carried and worn by personnel.
Fire fighters typically work under conditions in which smoke, smog, adverse weather conditions or darkness impair, if not totally obscure, normal vision. This presents a visual hindrance in rescue and fire fighting operations in locations such as a smoke filled building at night. Flash lights and other means of illumination can overcome darkness, but are virtually useless in smoky or dusty conditions. Radar, image intensifying (I.sup.2) systems, and infrared systems, respectfully, are conceptually not applicable because of typical close quarters encountered by the fire fighter, and the extreme and perturbed temperature contrasts caused by burning material and depth perception could be 5:1, 8:1 or greater on infrared (IR) systems or in adverse weather conditions, very difficult to maneuver around in hostile environments. Limited bad weather conditions can be handled by prior devices, but they generally fail in most adverse weather conditions. In performing their jobs, it is also critical that the fire fighter's hands be free. This requires any type of vision enhancement system to be "worn" by the fire fighters. Large prior art systems are not suited for fire fighting operations. A miners type head lamp is light in weight, would free the fire fighter's hands, and provide vision enhancement under conditions of darkness. Such a lamp would, as stated previously, be useless in smoky, dusty or foggy conditions. Systems are available which are relatively light in weight, can be worn by the user and enhance vision under limited or selected adverse conditions. These systems can be broadly classified as passive infrared (IR) systems and active I.sup.2 systems. Each class of systems will be discussed in detail in the following paragraphs.
Prior art passive IR based systems and include equipment IR hand held cameras made by Safety Specialist Inc., Raytheon, and ITT. Raytheon, Hytek International, ITT, FLIR and Nikon also markets IR sensing goggles, binoculars, monoculars or hand held systems. The Russian military also produced a variety of IR based systems, and these systems are now available as military surplus. These systems have very poor night vision capabilities, repairs are difficult, and replacement parts are usually difficult to obtain.
All of the IR based systems referenced above will work, as passive units, only in complete darkness in proper or selected weather conditions. Most prior art I.sup.2 systems use a red laser or a red or a near IR light beam to compensate for low light conditions or for no light conditions. The display viewed by the user of the referenced prior art systems will be either green or red with very poor resolution display, and the distance at which any of the referenced prior art systems can 100 percent recognize, verify and identify a subject (such as friendly or hostile personnel in military operations) is a very short.
Passive IR based systems do not use an external light beam for illumination of a target but, in turn, require radiated IR wave forms from an object or subject to have the capability of capturing and constructing a heat image signature from these passive light wave patterns. Using the image captured by a passive IR system (ghosting), it is very hard to verify the heat signature of a jackrabbit, a cow, a horse, a deer, or a human at distances from only 20 yards to one mile, depending upon the ambient temperature. As stated previously, such systems will simply not work in adverse weather conditions because the IR wave patterns given off by objects or subjects are absorbed by water droplets in the air. This confuses a passive IR system and "blanks" the image display. Passive IR systems will also not work in a very hot terrain environment because the temperature differential between the background and the target under surveillance are close to the same temperature signature being radiated. This small or insignificant temperature confuses the IR system, and "whites out" the image being viewed by the user.
I.sup.2 systems are active systems which require external near IR light sources to illuminate the target (such as stars, the moon, red near IR or laser light beam) to be able to intensify the light source with charged phosphorous gasses to capture a green or red visible image for viewing by a user. This technique is not considered "ghosting", but it is very close to "ghosting. The depth perception on these I.sup.2 systems could be 3:1, 5:1, 8:1 or greater depending on the "X" magnification factor used to see in the dark only. Stated another way, magnification is required to obtain an image, and the magnification process destroys true depth perception of the user. To use this type of system in a hostile environment will exponentially degrade the user's safety and efficiency factors. Resolution of prior art I.sup.2 systems is less than 300 horizontal television (TV) lines, which can result in eye strain to the user after five to ten minutes of use or less, in addition to vertigo. Also, system failure is experienced with bright light. Furthermore, 3D and virtual reality are also experienced by the user of these systems. Extensive user training is required to compensate for depth perception and poor imaging display quality in order to permit the user to recognize, verify and identify an object or subject. When viewing an image with prior art I.sup.2 systems at a distance of 20 yards or more, only the outline of the image is viewed which, again, is not "ghosting", but close to "ghosting". This prevents positive recognition, verification or identification of the viewed object or subject.
Generally speaking, prior art image enhancement systems, when used in adverse weather conditions or in complete darkness, are virtually useless without direct and intense illumination from an external light source. Furthermore, for either passive IR or I.sup.2 systems to be used in the dark, weather conditions must be in the proper format for these systems to be effective in the dark. All of these systems provide enhanced images to the user which are lacking the proper sizing and perspective of the viewed object. As an example, a person viewed with a Raytheon or FLIR or ITT or SSI-Vision I system under ideal moon light, star bright, star light night illumination conditions, may appear to be only twenty feet away but, in fact, is 100 feet away from the viewer. Stated another way, enhance images viewed by the user of Raytheon or FLIR or ITT or SSI-Vision I systems lack the proper size and perspective, and therefore prevent the user from correctly and accurately identifying and ranging the viewed object. In view of the above background, an object of the present invention is to provide an enhanced imaging system which provides both black and white or color images and which is effective under any adverse weather conditions affecting normal vision such as darkness, dust, fire, smoke, fog and the like.
Another object of the present invention is to provide an enhanced imaging system which is light weight and can be worn comfortably by a user.
Yet another object of the present invention is to provide an enhanced imaging system which is fully adjustable by the user for optimum viewing. Adjustments include brightness, contrast, tint, color and sharpness of the viewed image.
Another object of the present invention is to provide an enhanced imaging system which produces images to the user which are true in perspective and scale.
Another object of the present invention is to provide a system that operated properly when encountering bright lights.
Still other objects of the present invention is to provide an enhanced imaging system which is rugged, has self contained power for operation, and provides optional audio capabilities which enables the user to hear audio signals either from a remote transmitter or amplified sounds from the surrounding environs.
There are other objects and applications of the present invention which will become apparent in the following disclosure.